QRegion from QPolygon border issue

Hello,

I'm developing a little game that uses QPolygons as game-elements. These polygons may change position on the screen (it's a board-game), thus paintEvent is called whenever this happens. Since a QPolygon can be promoted to a QRegion through one of QRegions constructors, it is possible to pass the polygon that needs updating to the QWidget::update() function in order to only update this area and avoid redrawing the entire screen. However, on constructing a QRegion from a QPolygon, it seems that only the inside of the QPolygon is taken in account. For example, when removing such a polygon from the screen (i.e. redrawing the background), some of the border of the polygon (a black edge) remains! Does anyone have a suggestion on how to fix this?
I considered redrawing the entire boundingRect() of the polygon, but this brings a lot of inconveniences along with it...

Cheers,

Joren

I'm guessing you have to account for pen width used to draw that polygon but I'm not sure how you would do that.